One of the goals of periodontal reconstructive therapy is to establish treatment modalities that predictably restore periodontal tissues, i.e. bone, cementum and a functional periodontal ligament (PDL), lost as a consequence of disease. An attractive approach to determining the required factors and cells for regenerating periodontal tissues is to ascertain the factors necessary for their development. We hypothesize that during formation of the periodontium, bone morphogenetic protein-3 (BMP3) acts as a negative regulator of mineralization and amelogenin acts as a positive regulator of mineralization, through their ability to modulate the expression of bone sialoprotein (BSP) and osteocalcin (OCN), thus allowing for formation of cementum and a functional PDL. This hypothesis is supported by existing data that: 1) amelogenin enhances expression of transcripts fro Cbfal, BSP and OCN, in vitro; 2) ameolgenin null mice lack transcripts for BSP; 3) follicle cells express transcripts for BMP2 and 3; and 4) BMP2 promotes follicle cell differentiation toward a cementoblast/osteoblast phenotype, while BMP3 acts as a negative regulator of mineralization. Two specific aims will test this hypothesis. The first aim will establish the signal transduction pathways and transcription factors by which amelogenin regulates follicle cell behavior, in vitro. The second aim is targeted at defining the BMP3 signal transduction pathways and transcription factors involved in regulating the balance between maturation of follicle cells toward an osteoblast/cementoblast phenotype and toward PDL fibroblasts. Results from these studies will provide important data as to the regulators of ligament formation versus mineralization. This information is necessary for designing regenerative therapies based on sound biological principles.